PHP Codeigniter Uploading Class, rename files with specific schema

Question

I am having a spot of trouble with Codeigniter and getting files to rename within the upload process from the Upload Library it has to offer. Now before anyone says it, I am not looking for "encrypted" file names.

My Problem is in uploading images you have a good handful of types you could be dealing with. So how does one change the file name using the file_name config option to a specific schema (which I already have the schema part up and working). But maintain the same file type?

Right now I am attempting

$upload_config['file_name'] = $generated_filename_from_schema

Only problem is $generated_filename_from_schema doesnt have a file extension, and leaving the file extension out of the equation CI seems to ignore it altogether and just takes the file and append_1, _2, _3 as it goes up if the files have the same name, otherwise it just leaves the name intact.

Now I have to pass the $config to CI so it will upload the file, but how can I determin what kind of file I am working with before it trys to upload so I can use my name generation schema.

*edit*

    $upload_config['upload_path'] = realpath(APPPATH.'../images/');
    $upload_config['allowed_types'] = 'gif|jpg|png';
    $upload_config['max_size']  = 0;
    $upload_config['max_width'] = 0;
    $upload_config['max_height'] = 0;
    $upload_config['remove_spaces'] = true;

    $upload_config['file_name'] = $this->genfunc->genFileName($uid);

    if($this->input->post('uploads'))
    {

        $this->load->library('upload');
        $this->upload->initialize($upload_config);

        if (!$this->upload->do_upload())
        {
            //echo 'error';
            echo $config['upload_path'];
            $this->data['errors'] = $this->upload->display_errors();
        }
        else
        {
            //echo 'uploaded';
            $this->data['upload_data'] = $this->upload->data();
        }
    }

Answer 1

You can use $_FILES array to get original name of file.

Extract extension of original file.Then, append to your new file name.

Try as below

$ext = end(explode(".", $_FILES[$input_file_field_name]['name']));
$upload_config['file_name'] = $this->genfunc->genFileName($uid).'.'.$ext;

Answer 2

Personally, I find CodeIgniter's file uploading class to be somewhat cumbersome. If you want a vanilla PHP solution:

function submit_image(){
    $f = $_FILES['image'];
    $allowedTypes = array(IMAGETYPE_PNG, IMAGETYPE_JPEG, IMAGETYPE_GIF);
    $detectedType = exif_imagetype($f['tmp_name']);
    if(in_array($detectedType, $allowedTypes)){
        $pi = pathinfo($f['name']);
        $ext = $pi['extension'];
        $target = $this->genfunc->genFileName($uid) "." . $ext;
        if(move_uploaded_file($f['tmp_name'], $target)){
            /*success*/
        }
        else {/*couldn't save the file (perhaps permission error?*/}
    }
    else {/*invalid file type*/}
}